Probe head joint construction for endoscopically inserting ultrasound probe

ABSTRACT

A probe head joint construction for an endoscopically ultrasound probe to be introduced into a body cavity through a biopsy channel provided internally of an endoscopic insertion instrument, the ultrasound probe having a bulky ultrasound scanner head at the distal end of an elongated thin flexible cord having a cable sheathed in a soft flexible outer tube for placement in said endoscopic biopsy channel, and the ultrasound scanner head having an ultrasound transducer element housed in an end cap of a larger diameter than the endoscopic biopsy channel. The probe head joint construction according to the present invention essentially includes: a joint member of rigid metallic material extended on the proximal side of the end cap, and being formed in the shape of a hollow stepped cylinder including a front joint portion connected with the end cap and having a diameter substantially equivalent with that of the end cap, and a rear joint portion of a smaller diameter to be connected with the outer tube of the flexible cord by fitting engagement therewith, the rear joint portion being provided with a protuberance on the outer periphery thereof; the outer tube of the flexible cord being fitted on the rear joint portion of the joint member over and across the protuberance and firmly fastened to the rear joint portion by a couple of line wrappings formed therearound on front and rear sides of the protuberance.

FIELD OF THE ART

This invention relates generally to an ultrasound examination systememploying an endoscopically inserting ultrasound probe to be introducedinto a body cavity through a biopsy channel within an endoscopicinsertion instrument, and more particularly to a probe head jointconstruction particularly suitably for connecting a bulky ultrasoundscanner head securely to the distal end of an elongated flexible cord ofan endoscopically inserting ultrasound probe.

PRIOR ART

Regarding ultrasound examination systems in use for acquiringinformation on intracorporeal tissues, it has been known to introduce anendoscopically inserting ultrasound probe into a body cavity through anendoscopic instrument channel or a biopsy channel which is providedwithin an endoscopic insertion instrument. An ultrasound examinationsystem of this sort is largely constituted by an ultrasound probe, aprobe controller and an ultrasound image observation terminal. Formaking ultrasound scans, the ultrasound probe is provided with anultrasound scanner head at the tip end of a flexible cord. Theultrasound scanner head has an ultrasound transducer element housed inan end cap fixedly attached to the tip end of the flexible cord. Theprobe controller serves to control the operations of the ultrasoundtransducer element, and the ultrasound image observation terminalincludes an ultrasound driver which drives the ultrasound transducerelement for transmission of ultrasound pulses, along with a signalprocessor for processing received ultrasound echo signals intoultrasound images to be displayed on a monitor screen.

For placement in an endoscopic biopsy channel, a major part of theultrasound probe is constituted by a flexible cord of a smaller diameteras compared with the inside diameter of the endoscopic biopsy channel.In an ultrasound scanning operation, while transmitting ultrasound pulsesignals toward an intracorporeal portion of interest at predeterminedintervals, return echoes are received and converted into electricalsignals through the ultrasound transducer element to acquire informationof intracorporeal tissues over a predetermined range. The ultrasoundtransducer element is scanned in a linear direction in a linearultrasound scanning operation and in a radial or rotational direction ina radial ultrasound scanning operation. For a radial scan, theultrasound transducer element needs to be put in rotation by means of amotor or other rotational drive means, which however is too bulky to beprovided at the distal end of the ultrasound probe. Therefore, it is theusual practice to provide on the ultrasound probe a rotationtransmission means, which permits to remote-control the rotation of theultrasound transducer element, in cooperation with a rotational drivemeans and rotational angle detection means which are provided on thepart of the probe controller of the ultrasound examination system. Forthis purpose, the probe controller may be provided separately from anultrasound image observation terminal, or, if desired, may be assembledinto an ultrasound image observation terminal as an integral partthereof.

As the rotation transmission means, it has been the general practice toprovide on the ultrasound probe a flexible shaft which is connected tothe ultrasound transducer element at its fore end. The flexible shaft ofthis sort is usually in the form of a hollow coil tube consisting oflayers of tightly wound coils and internally providing a passage for acable to be connected to the ultrasound transducer element. The flexibleshaft is fitted in a flexible sheathing tube and rotatable therein totransmit its rotation to the distal end of the probe to rotate theultrasound transducer element.

The ultrasound probe is provided with a connector at its proximal endfor disconnectibly coupling same with the ultrasound controller. Theconnector is largely constituted by a fixed part which is connected tothe sheathing tube, and a rotating part which is connected to theflexible shaft through an internal space of the fixed part. The probecontroller is provided with a rotational shaft to be disconnectiblycoupled with the rotating part of the connector, along with a retainingmember which is located around the rotational shaft for fixedly holdingthe fixed part of the connector. A cable which is passed through theflexible shaft is electrically connected to the probe controller throughelectrode members provided in the rotating part. Accordingly, uponcoupling the rotating part of the connector with the rotational shaft onthe part of the probe controller, the electrodes of the rotating partare electrically connected with corresponding electrodes on the side ofthe rotational shaft.

The ultrasound scanner assembly at the distal end of the flexible cordof the probe has an ultrasound transducer element rotatably mountedwithin an end cap which connected to the sheathing tube of the flexiblecord. The ultrasound is supported on a rotary member which is connectedto the fore end of the flexible transmission shaft. The end cap of theultrasound scanner assembly is formed of a synthetic resin materialhaving excellent properties in acoustic characteristics, and itsinternal space is filled with an ultrasound transmission fluid medium.The end cap is securely fixed to the fore end of the flexible sheathingtube. The proximal end of the flexible cord is terminated with a tailend connector to be disconnectibly connected to the probe controller.The tail end connector is constituted by a ring-like stationary partwhich is connected to the sheathing tube, and a rotating part which islocated within the fixed part and connected to the flexible transmissionshaft. The stationary part of the tail end connector is fixedlyconnected to a stationary part of the probe controller, while therotating part is rotationally coupled with a rotational drive meansprovided on the probe controller. A cable to or from the ultrasoundtransducer element is passed through the flexible transmission shaft andelectrically connected with the probe controller through a pair ofelectrode members which are provided on the rotating part of theconnector and which are connectible with corresponding electrode memberson the part of the probe controller.

When the probe controller is operated to actuate the rotational drive ofthe rotational shaft, its rotation is transmitted to the flexible shaftthrough the rotating part of the connector, while the sheathing tubewhich is fitted on the flexible shaft is retained in a fixed statewithout rotating together with the flexible shaft. As will be understoodfrom the foregoing description, in addition to the function ofrotationally driving the flexible shaft, the probe controller hasfunctions as a signal relay means.

Since the outside diameter of the ultrasound probe is restricted by theinside diameter of an endoscopic biopsy channel on the endoscope, theultrasound transducer element can only have an active surface of alimited size for transmission and reception of ultrasound signals. Fromthe standpoint of permitting ultrasound scans of tissues in deeppositions, it is desirable for the ultrasound transducer element to haveas broad an active surface area as possible. In this connection, in thecase of a front loading type ultrasound probe which is designed to beplaced in an endoscopic biopsy channel from an inverse direction, thatis to say, from the fore distal end of an endoscopic insertioninstrument, it is possible to employ a bulky ultrasound scanner assemblywith a large-size ultrasound transducer element because in this casethere is no necessity for passing the ultrasound scanner assemblythrough the narrow endoscopic biopsy channel in a preparatory stageprior to introduction into a body cavity.

When an ultrasound probe is assembled into a biopsy channel of anendoscope, the ultrasound scanner head of the probe is projected to acertain extent from an exit opening of the biopsy channel at the distalend of the endoscopic insertion instrument. If an ensuing flexible cordportion is projected out of the endoscopic biopsy channel, letting theultrasound scanner head hang down unstably like a pendant, there mayarise difficulties in introducing the endoscopic insertion instrumentsmoothly into a body cavity or in locating the ultrasound scanner headprecisely in an aimed position within the body cavity. Therefore, theremust be provided some measures which can retain the ultrasound scannerhead stably at the distal end of the endoscopic insertion instrument. Inthis regard, if the projected flexible cord portion is retracted intothe endoscopic biopsy channel by pulling the probe in the rearwarddirection, the ultrasound scanner head which is larger than the insidediameter of the endoscopic biopsy channel can be fixedly held againstmarginal edges of the exit opening of the biopsy channel as long as thepulling force is applied to the probe.

The end cap which accommodates an ultrasound scanner head assembly isconnected to a sheathing tube of the flexible cord portion of the probenormally by the use of a joint ring member of a diameter substantiallysame as or slightly larger than the inside diameter of the sheathingtube. Normally, a fore end portion of the sheathing tube is fitted onand bonded to the joint ring member which is projected from the side ofthe end cap. In some cases, for the purpose of augmenting the strengthof the bonded joint portion, line wrapping is formed by winding a threador filament around the outer periphery of the sheathing tube. The endcap, which is formed of a synthetic resin material for excellentproperties in acoustic characteristics, can be easily deformed ifdirectly connected with the sheathing tube of the flexible cord,resulting in separation from the latter. For this reason, it is thegeneral practice to connect the end cap with the sheathing tube of theflexible cord through a connecting or joint member of rigid metallicmaterial, fitting the sheathing tube on the connecting member over asubstantial length.

The sheathing tube of the flexible cord is small in diameter and formedof a soft synthetic resin which is difficult to bond to the metallicconnecting member with sufficient strength of adhesion by the use of anadhesive. Even if line wrapping is formed on the connected end of thesheathing tube in addition to an adhesive, it still has a possibility ofbeing separated from the connecting member when an unduly large force isexerted thereon from outside. Therefore, when the flexible cord of theprobe is forcibly pulled into the endoscopic biopsy channel for thepurpose of holding the endoscopic scanner head fixedly against the foreend of the endoscopic insertion instrument as mentioned hereinbefore,the end cap of the scanner head can be caused to come off the sheathingtube of the flexible cord by a reaction force as it is pushed againstthe fore end of the endoscopic insertion instrument. The ultrasoundscanner head can be fixed at the fore end of the endoscopic insertioninstrument by providing a rubber ring or other stopper member around aflexible cord portion behind the ultrasound scanner head in such a wayit functions as a stopper for the scanner head by frictional contactwith inner surfaces of the endoscopic biopsy channel. Conversely,however, the provision of such stopper means makes it difficult toadjust the position of the ultrasound scanner head or to supply anultrasound transmission fluid medium such as deaerated water into a bodycavity through the endoscopic biopsy channel.

SUMMARY OF THE INVENTION

With the foregoing situations in view, it is an object of the presentinvention to provide a probe head joint construction for anendoscopically inserting ultrasound probe, which can prevent an end capof an ultrasound scanner head from falling off a distal end portion of aflexible cord of the probe.

It is another object of the present invention to provide a probe headjoint construction for an endoscopically inserting ultrasound probe,which can retain a bulky ultrasound scanner head, larger in diameterthan an endoscopic biopsy channel, stably at a distal end of anelongated flexible cord of the probe.

It is still another object of the invention to provide a probe headjoint construction for an endoscopically inserting ultrasound probe,which can retain a bulky ultrasound scanner head, larger in diameterthan an endoscopic biopsy channel, stably and securely at a distal endof an elongated flexible cord of the probe despite application of anaxial tensioning force which is constantly applied to the flexible cordto abut the scanner head against marginal edges of a front opening ofthe endoscopic biopsy channel.

In accordance with the present invention, there is provided a probe headjoint construction for an endoscopically ultrasound probe to beintroduced into a body cavity through a biopsy channel providedinternally of an endoscopic insertion instrument, the ultrasound probehaving a bulky ultrasound scanner head at the distal end of an elongatedthin flexible cord having a cable sheathed in a soft flexible outer tubefor placement in said endoscopic biopsy channel, and the ultrasoundscanner head having an ultrasound transducer element housed in an endcap of a larger diameter than the endoscopic biopsy channel. The probehead joint construction according to the present invention essentiallyincludes: a joint member of rigid metallic material extended on theproximal side of the end cap, and being formed in the shape of a hollowstepped cylinder including a front joint portion connected with the endcap and having a diameter substantially equivalent with that of the endcap, and a rear joint portion of a smaller diameter to be connected withthe outer tube of the flexible cord by fitting engagement therewith, therear joint portion being provided with a protuberance on the outerperiphery thereof; the outer tube of the flexible cord being fitted onthe rear joint portion of the joint member over and across theprotuberance and firmly fastened to the rear joint portion by a coupleof line wrappings formed therearound on front and rear sides of theprotuberance.

Preferably, the protuberance is an annular protuberance providedapproximately in an axially intermediate position on the circumferenceof the rear joint portion, and the line wrapping on the front side ofthe protuberance has a greater number of turns than the line wrapping onthe rear side of the protuberance. In order for the outer tube of theflexible cord to present a smooth profile in the joint portion, a sunkenportion of reduced diameter is provided on the outer periphery of thetube on which the line wrappings are to be formed.

The above and other objects, features and advantages of the presentinvention will become apparent from the following particular descriptionof the invention, taken in conjunction with the accompanying drawingswhich show by way of example some preferred embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a schematic illustration of the general layout of anultrasound examination system with an endoscopically insertingultrasound probe;

FIG. 2 is a fragmentary schematic view of an ultrasound probe and acoupling adaptor;

FIG. 3 is a fragmentary longitudinal section of a fore end portion ofthe ultrasound probe, with a stopper mechanism omitted for the sake ofillustration of the ultrasound probe itself;

FIG. 4 is a longitudinal sectional view taken on line X--X of FIG. 3;

FIG. 5 is a longitudinal sectional view of a tail end portion of theultrasound probe;

FIG. 6 is a schematic sectional view of a probe controller;

FIG. 7 is a schematic view of a probe clamper;

FIG. 8 is a longitudinal sectional view of the coupling adaptor;

FIG. 9 is a schematic sectional view of the ultrasound probe which iscoupled with the probe controller through the coupling adaptor; and

FIG. 10 is a schematic sectional view of a joint portion of theultrasound scanner head and flexible cord of the probe.

DESCRIPTION OF PREFERRED EMBODIMENTS

Hereafter, the present invention is described more particularly by wayof its preferred embodiments shown in the drawings. Schematically shownin FIG. 1 is the general layout of an ultrasound examination systemincorporating an ultrasound probe coupling adaptor according to thepresent invention. The ultrasound examination system is largely composedof an ultrasound probe 1, a probe controller 2 and an ultrasound imageobservation terminal 3 with a monitor screen 4. The ultrasound probe 1is of the type which is introduced into a body cavity by way of anendoscope 5, more specifically, by way of a biopsy channel 6 which isprovided axially and internally of an endoscopic insertion instrument 5band accessible through an entrance housing 6a, which is provided on amanipulating head grip 5a of the endoscope 5. Led out from themanipulating head grip 5a of the endoscope 5 is a universal cable 5c tobe connected to a light source and an ultrasound signal processor whichare not shown in the drawings.

The ultrasound probe 1 as a whole is constructed as shown in FIG. 2.More specifically, as seen in FIG. 2, the ultrasound probe 1 is largelyconstituted by an ultrasound scanner head assembly 1a, a flexible cord1b and a tail end connector 1c. As shown particularly in FIGS. 3 and 4,the ultrasound scanner head la is provided with an end cap 10. Connectedto the end cap 10 is a joint member 11 which is formed of a rigidmetallic material in the form of a hollow stepped cylinder having afront joint portion 11a of a large diameter and a rear joint portion 11bof a small diameter. The ultrasound transducer element 12 accommodatedin the end cap 10, and mounted on a rotary member 13 which is rotatablysupported within the end cap 10 through a bearing 14 to scan theultrasound transducer element 12 in the radial direction. Foraccommodating a large-size ultrasound transducer element with a broadactive surface area which can transmit strong ultrasound signals, theend cap 10 is of a bulky size having an outside diameter as larger thanthe inside diameter of the endoscopic biopsy channel 7 as possiblewithin a range which would not obstruct the view field of endoscopicobservation.

The flexible cord 1b is constituted by a flexible outer tube 15 of softsynthetic resin material or the like, and a flexible rotationtransmission shaft 16 which is sheathed in the outer tube 15. Fixedlyconnected to the fore distal end of the outer tube 15 is the jointmember 11 which is in turn fixedly connected to the end cap 10 at theopposite end thereof. The flexible transmission shaft 16 is constituted,for example, by tightly wound coils, preferably, by double layers oftightly wound coils of metal wires for transmitting rotations accuratelyin a reliable manner. The fore end of the outer tube 15 is fitted on therear joint portion 11b of the joint member 11 and securely fastened tothe latter by line wrapping 17, thereby fixedly connecting the end cap10 at the fore end of the flexible cord 1b. The fore distal end of theflexible shaft 16 is securely fixed to a hollow rotary member 18 whichis integrally connected to the rotary member 13. The ultrasoundtransducer element 12 is provided with a pair of electrodes 19a and 19bto connect signal lines 20a and 20b of a coaxial cable 20 which ispassed through the neck member 18 and extended as far ss the tail endconnector 1c of the probe 1 through the internal space of the flexibleshaft 16.

Shown on an enlarged scale in FIG. 5 is the probe construction where theproximal end of the flexible cord 1b is terminated with the tail endconnector 1c. More specifically, the proximal end of the outer tube 15is fixedly fitted on a rigid pipe 21 of metal. The proximal end of theflexible shaft 16 is connected to a rotational ring assembly 22including an electrode ring. In this instance, the ring assembly 22 iscomposed of four rotary members or rings 23 to 26 which are successivelythreaded one in another in the axial direction. The first rotary ring 23which is directly connected to the flexible shaft 16 is formed of arigid metallic material with a sufficient degree of shape retainabilityand received in the rigid pipe 21, which is similarly formed of a rigidmetallic material, for sliding rotational movements therein. A sealmember 27 is fitted on the first rotary ring 23 to seal off theclearance between the first rotary ring 23 and the rigid pipe 21 air-and liquid-tight. Connected to the first rotary ring 23 is a secondrotary ring 24 which is formed of an electrically insulating materialsuch as a synthetic resin material or the like. A third rotary ring 25which is connected to the second rotary ring 24 is formed of a metal orother conducting material, while a fourth rotary member 26 which isconnected to the third rotary ring 25 is formed of an electricallyinsulating material.

In this case, for the purpose of ensuring the sealing capacity by theseal member 27, the first rotary ring 23 is formed of a metal ormetallic material. The third rotary ring 25 is formed of a metal becauseit is required to function as an electrode to be connected to theultrasound transducer element 12. Accordingly, the second and fourthrotary members 24 and 26 of electrically insulating material are locatedon the front and rear sides of the third rotary ring 25. The coaxialcable 20 is passed internally through the ring assembly 22, with itscore wire 20c connected to a pin 28, which is fitted in the fourthrotary member 26, and its shield wire 20d connected to the third rotaryring 25.

Further, a rotation transmission pin 29 is securely planted in the thirdrotary ring 25. As described hereinlater, the transmission pin 29functions to transmit rotation to the ring assembly 22, and is arrangedin such a way as to project radially outward from the outer periphery ofthe third rotary ring 25 by a predetermined length. A spacer ring 30 isfitted on the outer periphery of the ring assembly 22 between therotation transmission pin 29 and the rigid pipe 21. This spacer ring 30is abutted against the front side of the rotation transmission pin 29and rear end face of the retainer shell 21, thereby to retain the ringassembly 22, the flexible shaft 16 which is connected to the ringassembly 22, the flexible tube 16 and the retainer shell 21 in aninseparably assembled state. The spacer ring 30 is formed of anelectrically insulating synthetic resin material or the like withsuitable slipperiness. Thus, by the spacer ring 30, the retainer shell21 is electrically insulated from the third rotary ring 25 and therotation transmission pin 29 which are both formed of a metallicmaterial.

Referring now to FIG. 6, the probe controller 21 is provided with acasing 31 of an electrically insulating synthetic resin material or thelike, in which a rotational shaft 32 is rotatably mounted through abearing 33 to extend toward an opening 31a which is provided on thefront side of the casing 31. Mounted on the rotational shaft 32 are apair of gears 34 and 35. One gear 34 is meshed with a drive gear 37which is mounted on an output shaft of an electric motor 36, while theother gear 35 is meshed with a follower gear 39 which is mounted on aninput shaft of an encoder 38. Provided internally of the rotationalshaft 32 is an electrode member 40 which is constituted by an inner pipe41 and an outer pipe 42. These inner and outer pipes 41 and 42 areformed of an electrically conducting material and insulated from eachother by an interposed insulating pipe 43. In addition, the outer pipe42 is fitted in an insulating ring 44 which is fixedly fitted in therotational shaft 32. Thus, by an adaptor 60 which will be describedhereinlater, the core and shield wires 20c and 20d of the coaxial cable20 are electrically connected to the inner and outer pipes 41 and 42,respectively.

The probe controller 2 which is arranged in the above-described manneris removably attached on the entrance passage 6 of the biopsy channel 7,which is provided on the housing of the manipulating head grip 5a of theendoscope 5. For this purpose, a cylindrical connecting piece 43 isprovided on an arm 44 which is projected outward from the casing 31 ofthe probe controller 2, and removably fitted in an opening 8 of theentrance passage 6 of the endoscopic head grip 5a. The arm 44 isprovided with hooks 45 to be detachably engaged with a flange 8a portionwhich is formed around the entrance opening 8 of the endoscopic biopsychannel 7 (FIG. 1). The hooks 45 are urged to embrace the flange portion8a by the action of springs, which are not shown in the drawings,thereby to hold the probe controller 2 of the ultrasound probe 1 fixedlyon the head grip 5a of the endoscope 5.

As seen in FIG. 1, the tail end connector 1c and ensuing proximal endportion of the flexible cord 1b of the ultrasound probe 1 are led out ofthe endoscopic biopsy channel 7 through an axial passage in theconnecting piece 43 which is fitted in the entrance housing 6, andconnected to a tensioning means 46. The proximal end portion of theflexible cord 1b behind the tensioning means 46 is loosely looped andconnected to the probe controller 2 through a coupling adaptor 60. Thetensioning means 46 includes an operating rod 46a which is provided witha probe clamp member 46b.

As clear from FIG. 7, the probe clamp member 46b is comprised of an arm50 which is extended from the operating rod 46a, and an axially splitholder pipe 51 is 5 which is gripped in a fore end portion of the arm50. In turn, the flexible cord 1b coming out of the endoscopic biopsychannel 7 is passed through and releasably gripped in the holder pipe51. Fitted on the holder pipe 51 is a clamp ring 52 which has flat claspportions 52a at its opposite ends releasably fastened to each other by ascrew 53. It follows that a proximal end portion of the flexible cord 1bof the ultrasound probe 1, outside the endoscopic biopsy channel 7, canbe fixedly clamped by the clamp member 46b at an arbitrary position. Theoperating rod 46a is retractably mounted on the casing 31 of the probecontroller 2, and constantly urged to protrude in the outward directionby the action of a spring 47 which is provided within the casing 31. Theoperating rod 46a can be pushed into and out of the casing 31 by way ofa finger ring 46c which is provided at its outer end. Accordingly, whena proximal end portion of the flexible cord 1b is fixedly clamped by theclamp member 46b, the ultrasound probe 1 as a whole is constantly urgedto retract toward the proximal end of the endoscopic biopsy channel 7under the influence of the biasing action of the spring 47.

One end of the rotational shaft 32 is disposed in the opening 31a on thefront side of the casing 31 as mentioned hereinbefore, while the otherend of the rotational shaft 32 is connected to a rotary member 48a of arotary connector 48 which is provided within the casing 31. A cable 9afrom the cable assembly 9 is connected to a stationary member 48b of therotary connector 48. Further, the stationary member 48b of the rotaryconnector 48 is fitted in a rotation blocking member 48c and therebyblocked against rotational movements with the rotary member and at thesame time prevented from twisting or torsional deformations. Acylindrical connection housing 49 is erected around the opening 31a ofthe housing 31 in such a way as to circumvent the rotational shaft 32.

The tail end connector 1c of the ultrasound probe 1 is coupled with theabove-described probe controller 2 not directly but through a couplingadaptor 60 as described below. The coupling adaptor 60 is provided witha first or front coupling mechanism at one end to be connected to thetail end connector 1c of the probe and a second or rear couplingmechanism at the other end to be connected to the probe controller 2.More specifically, as shown particularly in FIG. 8, the coupling adaptor60 is provided with stationary members including an outer housing 61 ofsubstantially cylindrical shape and a retainer cap 62 which is threadedinto one end of the outer housing 61. These stationary members of theadaptor are securely fixable relative to the casing 31 of the probecontroller 2. To this end, the outer housing 61 is provided with astopper groove 61a which is engaged with a stopper projection 49a on thepart of the connection housing 49 of the probe controller 2 to blockrelative rotations of the fixed member of the adaptor 60 when connectedto the latter. Further, the retainer cap 52 of the adaptor 60 isprovided with an axial hole 62a to receive the retainer shell 21 of thetail end connector 1c of the probe 1. The retainer cap 62 is providedwith a plural number of radial through holes 62b in its front end wallacross the axial hole 62a to receive fixing screws 63, which areretractably protrudable into the axial hole 62a. More specifically, thefixing screws 63 are urged into the protruding positions by biasingsprings 65 which are charged between the respective fixing screws 63 andspring seats 64. The fixing screws 63 are pointed at the respectiveinner ends for engagement in axial grooves (not shown) which areprovided on the outer peripheral surface of the retainer shell 21 of thetail end connector 1c as rotation blocking grooves. When tail endconnector 1c is inserted into the axial hole 62a of the retainer cap 62up to the retainer shell 21, the pointed ends of the fixing screws 63are engaged with the stopper grooves to block rotations of the retainershell 21 and the outer tube 16 of the probe 1 during radial ultrasoundscans when the ultrasound transducer element 13 is rotated through theflexible shaft 17.

The coupling adaptor 60 is further provided with rotary membersinternally of its stationary members including the housing 61 and theretainer cap 62. Major rotary members are rear and front rotary members66 and 67 of generally hollow cylindrical shapes. A socket assembly 68is threaded into the front rotary member 67 to receive the tail endconnector 1c of the ultrasound probe 1 therein. The front rotary member67 itself is threaded into a retainer ring 69 which is fixedly connectedto the rear rotary member 66 by a box nut 70. A first tubular electrodepin 71 of the socket assembly is threaded into the front rotary member67, which is formed of an electrically insulating material. A tubularinsulating member 72 is threaded into the first tubular electrode pin71, and a second tubular electrode pin 73 is fitted in this tubularinsulating member 72. The first and second electrode pins 71 and 73 arein the form of axially split pins with spring characteristics. Further,a radial drive pin 74 is provided on the front rotary is 5 member 67,the drive pin 74 being abutted against the rotation transmission pin 29on the part of the tail end connector 1c of the ultrasound probe 1 whenthe latter is connected to the coupling adaptor 60. By abuttingengagement of the drive pin 74 with the rotation transmission pin 29,rotation is transmitted from the rotary members of the coupling adaptor60 to the ring assembly 22 on the tail end connector 1c. Thus, aninterlocked rotation transmission mechanism is constituted by the drivepin 74 and the transmission pin 29.

On the other hand, a C-ring 75 is fitted on a proximal end portion ofthe rear rotary member 66, the C-ring 75 being engageable with anannular groove 32a around the inner periphery of a larger-diametercoupling portion, which is provided at the outer or front end of therotational shaft 32, for retaining the adaptor 60 securely in theconnected position relative to the probe controller 2, precluding thepossibilities of its dislocations. Further, the distal end portion ofthe rear rotary member 66, on the proximal side of the C-ring, is formedin a spline profile for engagement in the inner periphery 32b of anouter end portion of the rotational shaft 32 which is formed in acorresponding spline profile. Indicated at 77 is a connector memberwhich is fixedly provided within the rear rotary member 66. Thisconnector member 77 is constituted by a tubular outer cover 78 and anelectrode rod 79, each formed of a conducting material. An insulatingring 80 is interposed between the outer cover 78 and the electrode rod79 which are connected to the first and second tubular electrodes 71 and73 through wires 81 and 82, respectively. Both of the outer cover 78 andelectrode rod 79 are in the form of an axially split tubular structure,and are resiliently coupled with the first and second tubular electrodes71 and 73, respectively. The rotary and stationary members may beassembled together through a bearing. In this particular embodiment, thehousing 61 and the rear rotary member 66 are retained in small gaprelation with each other. In case the rear rotary member 66 is looselyfitted in the housing 61 in this manner, the connector member 77 can beeasily and snugly fitted in the rotational shaft 32 as the housing 61 isbrought into engagement with the connection housing 49 on the part ofthe probe controller 2.

With the probe coupling adaptor of the construction as described above,for the purpose of transmitting ultrasound signals of lower frequencyand higher power, the ultrasound probe 1 can employ an ultrasoundtransducer element 13 of a large size having a broader active surfacearea within the end cap 10 of on the ultrasound scanner assembly whichis much larger than the inside diameter of the biopsy channel 7 on theendoscope 5.

In a preparatory stage prior to introduction into a body cavity of theinsertion instrument 5b of the endoscope 5, the ultrasound probe 1 isplaced in the endoscopic biopsy channel 7 through an opening at thedistal end of the endoscopic insertion instrument 5b, drawing out thetail end connector 1c through the entrance way 6 on the manipulatinghead grip 5a of the endoscope 5. The proximal end portion of theflexible cord 1b, including the tail end connector 1c, which has beendrawn out of the endoscopic biopsy channel 7 is threaded through theaxial passage 43a in the connecting piece 43 on the probe controller 2.The flexible cord 1b is then clamped in the clamp member 46b of thetensioning means 46 at a suitable position before coupling the tail endconnector 1c with the coupling adaptor 60. After this, the couplingadaptor 60 is connected to the probe controller 2. As a result, as shownin FIG. 9, the ultrasound probe 1 is electrically and rotationallycoupled with the probe controller 2 through the coupling adaptor 60,permitting to rotationally drive the ultrasound transducer element 12from the probe controller 2 and to transfer electrical signals betweenthe ultrasound transducer element 12 and the ultrasound imageobservation terminal 3.

More specifically, upon connecting the rear rotary member 66 and housing61 of the adaptor 60 with the rotational shaft 32 and connection housing49 on the casing 31 of the probe controller 2, respectively, theconnector member 77 is coupled with the electrode member 40 on the probecontroller 2. Consequently, rotation of the rotational shaft 32 istransmitted to the ring assembly 22 of the ultrasound probe 2 throughthe rear and front rotary members 66 and 67 of the adaptor 60, and thento the flexible transmission shaft 16 which is connected with therotating ring assembly 22. The signal lines 20a and 20b of the coaxialcable 20, to and from the ultrasound transducer element 13, areelectrically connected with the first and second tubular electrodes 71and 73 through the electrode pin 28 and the transmission pin 29, whichare electrically connected with the inner and outer cover tubes 79 and78 of the connector member 77 and the inner and outer pieces 41 and 42of the electrode member 40 on the probe controller 2 through the wires81 and 82, which are electrically connected with the ultrasound imageobservation terminal 3 through the rotary connector 48 and the cable 9.

In order to carry out an ultrasound scan or scans, after introducing theinsertion instrument 5b of the endoscope into an intracavitaryexamination site, the ultrasound scanner assembly 1a which is projectedfrom the distal end of the endoscopic insertion instrument 5b is abuttedagainst an intracavitary wall. Then, the ultrasound transducer element12 is put in rotation by remote control from the probe controller 2. Atthe same time the ultrasound transducer element 12 is driven to transmitultrasound pulses into the patient's body at predetermined angularintervals, while converting received return echoes into electricalsignals. At the ultrasound image observation terminal 3, the return echosignals from the ultrasound transducer element 12 are processed intovideo signals to display ultrasound images of body tissues on themonitor screen 4.

Thus, during a scanning operation, the ultrasound scanner head 1a of theprobe 1 in the biopsy channel 7 of the endoscope 5 is projected from thedistal end of the endoscopic insertion instrument 5b. However, if atthis time part of the flexible cord 1b is also projected from theendoscopic insertion instrument 5b, it becomes extremely difficult tocontrol the position of the ultrasound scanner head 1a, which is allowedto hang down unstably from the distal end of the endoscopic insertioninstrument. This unstable state of the scanner head 1a makes itdifficult not only to introduce the endoscopic insertion instrumentsmoothly into an intracavitary examination site but also to orient theultrasound scanner head 1a toward an intracavitary region to beexamined. Therefore, at the time of a scanning operation, the ultrasoundscanner head 1a should be fixedly retained at the distal end of theendoscopic insertion instrument 5b substantially as an integral part ofthe latter. The fixation of the ultrasound scanner head 1a integrally atthe distal end of the endoscopic insertion instrument 5b has a greatimportance in consideration of the fact that the endoscope 5 is usuallyprovided with an angle section in a fore end portion of its insertioninstrument for angularly flexing the fore end of the insertioninstrument toward a desired direction, permitting to turn the ultrasoundscanner head 1a into the desired direction simultaneously with theflexing operation on the angle section of the endoscope 5.

For this purpose, the flexible cord 1b of the ultrasound probe 1 isconstantly applied with a predetermined tensioning force by thetensioning means 46 which is provided on the probe controller 2, urgingthe flexible cord 1b to retract into the endoscopic biopsy channel 7. Inorder to apply a tension to the flexible cord 1b of the probe 1, theoperating rod 46 is pushed into the casing 31 by way of the finger ring46c before clamping a predetermined proximal end portion of the flexiblecord 1b in the probe clamp member 46b. In this state, upon releasing thefinger ring 46c, the operating rod 46a is pushed back into the outerprojecting position by the action of the biasing spring 47, therebyapplying to the flexible cord 1b a tensioning force acting to retractthe flexible cord 1b into the endoscopic biopsy channel 7 until theultrasound scanner head 1a is abutted against the distal end face of theendoscopic insertion instrument 5b. At this time, since the ultrasoundscanner head assembly 1a is larger than the inside diameter of theendoscopic biopsy channel 7, it is pushed against marginal edge portionsof the exit opening of the biopsy channel 7 and fixedly held against thedistal end face of the endoscopic insertion instrument 5b.

However, if the ultrasound scanner head 1a is pushed directly againstthe distal end face of the endoscopic insertion instrument 5b, theultrasound scanner head 1a can be subjected to a reaction force whichacts to pull the scanner head 1a way from the flexible cord 1b, that isto say, to disjoin the scanner head 1a from the flexible cord 1b. Moreparticularly, as the radial surface 11c of the joint member 11 isdirectly pressed against the distal end face of the endoscopic inseritoninstrument 5b, the rear joint portion 11b of the joint member 11 whichis fitting engagement with the outer tube 15 of the flexible cord 1bcould be disjoined from the latter by a reaction force. In order toprevent troubles of this sort, it is necessary to increase the strengthof the joint construction of the joint member 11, especially the rearjoint portion 11b of the joint member 11 in fitting engagement with theflexible cord 1b of the probe 1. According to the present invention, thestrength of the joint portion between the ultrasound scanner head 1a andthe outer tube 15 of the flexible cord 1b is improved by a jointconstruction as shown in FIG. 10.

Firstly, as seen in that figure, the rigid tip end section of theinsertion instrument 5b of the endoscope 5, which is connected to thefore end of the angle section, has a certain axial length to accommodatecomponents of an endoscopic image pickup system such as objective lens,solid-state image sensor etc. Since the ultrasound probe 1 is placed inthe endoscopic biopsy channel 7 when in us, a fore end portion of theprobe 1 to be located within the rigid tip end section of the endoscope5 is not necessarily required to have flexibility. Further, since theultrasound scanner head 1a of the probe 1, which is always projectedforward of the endoscopic biopsy channel 7, at least a fore end portionof the joint member 11 which is located within the rigid tip end sectionof the endoscopic insertion instrument 5b has no possibility of beingbent in a particular direction even if the step-like radial surface 11cof the joint member 11 is abutted against the distal end face of theendoscopic insertion instrument 5b. Therefore, the length of the rearjoint portion 11b of the joint member 11 of rigid metal is increased toa maximum possible length for the purpose of increasing the length ofits fitting engagement with the outer tube 15 of the flexible cord 1b.The increase in fitting engagement makes it possible to increase thejoint strength. The outer tube 15 is fitted on the rear joint portion 15of the joint member 11 and bonded to the latter by the use of anadhesive. In addition, line wrapping 17 is formed on the outer tube 15so that the tube 15 which is formed of a soft and flexible material iscompressed and tightly fastened to the outer periphery of the rear jointportion 11b.

Besides, the rear joint portion 11b is provided with an annularprotuberance 90 of a predetermined height around its outer peripherysubstantially at an axially intermediate position, more specifically, atan axially intermediate position a little closer to its proximal end.The outer tube 16 is fitted over and across the annular protuberance 90and extended as far as the radial surface 11c at the border between thefront and rear joint portions 11a and 11b of the joint member 11. Theabove-described line wrapping 17 is formed around the outer periphery ofthe outer tube 15 except the annular protuberance 90. In other words,the line wrapping 17 is divided into front line wrapping 17a and rearline wrapping 17b by the annular protuberance 90.

The front line wrapping 17a on the front side of the annularprotuberance 90 is formed fully to the distal end of the outer tube 15,but the rear line wrapping 17b on the rear side of the annularprotuberance 90 is terminated at a position short of the proximal end ofthe rear joint portion 11b. It is preferred for the rear line wrapping17b not to be extended to the proximal end of the rear joint portion 11bbecause, if extended, the strong fastening force of the line wrappingcould deform the joint portion. It follows that the front line wrapping17a has a greater number of turns and a larger width than the rear linewrapping 17b. Consequently, when the ultrasound probe 1 is assembledinto the endoscope 5, the joint portion has an extremely high strengthparticularly against a tensile force acting in the direction indicatedby an arrow in FIG. 10.

The outer tube 15 is firmly pressed against the rear joint portion 11bonly in those portions which are under the line wrapping 17, and theremainder of the tube 15 is free of the pressing force of the linewrapping 17. The tube portions which are gripped by the compressingforce of the front and rear line wrappings 17a and 17b are restrained ofaxial movements by the annular protuberance 90, which functions as astopper preventing the tube 15 from slipping along the surface of therear joint portion 11b of the joint member 11 even when a strong pullingforce is applied thereto. As a result, the joint strength of the outertube 15 and the rear joint portion 11b is enhanced to a considerabledegree to preclude the possibilities of the joined parts being separatedby the tensioning force which is constantly applied to the flexible cord1b of the probe 1 in a direction backward of the endoscopic biopsychannel 7 for retraction thereinto every time and all the time when theultrasound probe 1 is assembled into the endoscope 5 for an ultrasoundexamination.

The fore end portion of the outer sheathing tube 15 which is in fittingengagement with the rear joint portion 11b of the joint member 11 isdeformed to conform with the profile of the annular protuberance 90under the pressures of the front and rear line wrappings 17a and 17b.Obtrusive thickening or bulging of the outer tube 15 in this fitted foreend portion is not desirable because it may make it difficult to supplya liquid into a body cavity through a gap space or spaces between theflexible cord 1b and the inner surfaces of the endoscopic biopsy channel7. Therefore, for the purpose of preventing part of the fitting fore endportion of the outer tube 15 from bulging out in the radial direction,the outer tube 15 is thinned down to provide a sunken or portion 91 ofreduced diameter on the outer periphery of its fitting end portionsubstantially over the entire length thereof. In this regard, it isdesirable to reduce the thickness of the fitting end portion of theouter tube 15 to an extent which is slightly larger than the diameter ofthe filament or thread which is used for the line wrappings 17a and 17b.This reduction in thickness or diameter prevents the fitting end portionof the outer tube 15 from bulging out to any objectionable degree evenafter application of the line wrappings 17a and 17b and an adhesive 92which cements the respective line wrappings 17a and 17b in position onthe outer periphery of the outer tube 15. The annular stopperprotuberance 90 which is free of the line wrappings 17a and 17b wouldnot protrude radially outward of the remainder of the joint portion ifits radial height is limited to a measure corresponding to the amount ofreduction in diameter of the small diameter portion 91. Accordingly, thefore end portion of the outer sheathing tube 15 which is fitted on therear joint portion 11b can present a smooth profile almost free of upsand downs in radial directions. The annular protuberance 90 can functionas a stopper satisfactorily as long as it has a height corresponding tothe diameter of the thread or filament of the line wrappings 17a and17b.

What is claimed is:
 1. In an ultrasound probe to be introduced into abody cavity through a biopsy channel provided internally of anendoscopic insertion instrument, said ultrasound probe having a bulkyultrasound scanner head at the distal end of an elongated thin flexiblecord having a cable sheathed in a soft flexible outer tube for placementin said endoscopic biopsy channel, said ultrasound scanner head havingan ultrasound transducer element housed in an end cap of a largerdiameter than said endoscopic biopsy channel:a probe head jointconstruction, comprising: a joint member of rigid metallic materialextended on the proximal side of said end cap, and being formed in theshape of a hollow stepped cylinder including a front joint portionconnected with said end cap and having a diameter substantiallyequivalent with that of said end cap, and a rear joint portion of asmaller diameter to be connected with said outer tube of said flexiblecord by fitting engagement therewith, said rear joint portion beingprovided with a protuberance on the outer periphery thereof; said outertube of said flexible cord being fitted on said rear joint portion ofsaid joint member over and across said protuberance and firmly fastenedto said rear joint portion by a couple of line wrappings formedtherearound on front and rear sides of said protuberance.
 2. A probehead joint construction as defined in claim 1, wherein said protuberanceis an annular protuberance formed substantially in an axiallyintermediate position on said rear joint portion of said joint member.3. A probe head joint construction as defined in claim 1, wherein saidline wrapping on the front side of said protuberance has a greaternumber of turns than said line wrapping on the rear side of saidprotuberance.
 4. A probe head joint construction as defined in claim 1,wherein said outer tube is thinned down on the outer peripheral sidethereof in a fore end portion where said line wrappings are formedtherearound.